Field of the Invention
The present disclosure relates to an image forming apparatus such as a copier and a printer and a feeding device used in the apparatus and executing a feed control over a recording material therein.
Description of the Related Art
Conventionally, an image forming apparatus such as a copier and a printer has a cassette detachably attached to a main body of the image forming apparatus. Recording materials may be set in the cassette so that the recording materials can be fed sequentially to the main body of the image forming apparatus.
FIGS. 16A to 16E are sectional views of a cassette 10 according to International Publication No. WO/2011/007406. FIG. 16A illustrates a state that a plurality of recording materials S is set in the cassette 10. After a pickup roller 20 picks a first recording material S1, a feed roller 30 feeds the recording material S1 to a downstream side, as illustrated in FIG. 16B. According to International Publication No. WO/2011/007406, even after a rear end of the recording material S1 passes through the pickup roller 20, the pickup roller 20 keeps rotating. This then feeds a second recording material S2 simultaneously with the operation for feeding the recording material S1, as illustrated in FIG. 16C. A retard roller 40 and the feed roller 30 construct a separation nip Pfr which separates one from the plurality of recording materials S. Thus, as illustrated in FIG. 16D, when a leading end of the recording material S2 reaches the separation nip Pfr, the recording material S2 stops. The recording material S1 is only fed to the downstream side by the feed roller 30, and the operation for feeding the recording material S1 ends in the state as illustrated in FIG. 16E.
According to International Publication No. WO/2011/007406, it is controlled such that the position of the leading end of the recording material S2 taken out by an effect of friction and moving in an unintended direction in a range Ld illustrated in FIG. 16E can be adjusted to fit to the separation nip Pfr. The range Ld here is a range from an initial leading-end position Ps of a recording material S set in the cassette 10 to the separation nip Pfr. This control can reduce the distance (also called a sheet interval) between the rear end of the recording material S1 and the leading end of the recording material S2 and can increase the productivity of the image forming apparatus.
However, when the cassette 10 is drawn out in the state illustrated in FIG. 16E in order to replace the recording materials S accommodated in the cassette 10, there is a risk that the recording material S2 moving out from the cassette 10 may be wrinkled or folded or that the recording material S2 may be torn. Furthermore, because the recording material S2 is nipped by the feed roller 30 and the retard roller 40, there is a possibility that the recording material S2 may remain in the main body of the image forming apparatus when the cassette 10 is drawn out. If a user inserts the cassette 10 without noticing the presence of the recording material S2 remaining in the main body, the recording material S2 is jammed between the cassette 10 and the main body, which may prevent the image forming operation from starting.